Coronavirus: artificial respirators, the keystone of the medical response


In the “war” that hospitals are waging against the coronavirus, pending studies on a possible drug remedy, a device is essential: the artificial respirator. The scientific journal The Lancet, based on data collected in Wuhan, the epicenter of the pandemic, judged on February 24 that these devices were even “the main treatment” for critically ill patients.

What is an artificial respirator for?

Relay the lungs to supply oxygen to the blood. In many cases, the virus severely alters the airways to the point that an oxygen mask is no longer enough. “The membrane that forms the interface between air and blood is inflamed, damaged or even destroyed,” explains a hospital practitioner, specialized in emergency medicine, to To allow oxygen to circulate in the blood, it is therefore necessary to supplement the lungs in their transport work, the time for the membrane to heal.

What does it look like ?

There are several types of devices. In the emergency room, they are the size of a shoebox. In the intensive care units, they occupy the equivalent of a line basket, perched on a stand and accompanied by pipes. These large devices allow fine adjustments, essential for long-term ventilation. In France, Air Liquide manufactures two types in its workshops: in Pau (Pyrenees-Atlantiques), these are devices intended for home use, for chronic respiratory patients; in Antony (Hauts-de-Seine), heavy hospital appliances.

How does a respirator work?

“It is a big bellows with settings a little complicated”, caricature our emergency doctor. “The pulmonary membrane being damaged, the gas exchanges are less well, so we help the lungs so that a sufficient quantity of oxygen passes into the blood. The ambient air is composed of 21% oxygen; with these machines, the air can be enriched by up to 100%, useful in the acute phase. In addition, they replace the patient’s respiratory muscles, which become exhausted. ” Each patient is connected to his machine by a mask or by a tube slipped into the trachea. Blood samples are regularly taken to measure the amount of oxygen thus injected.

Why should patients on ventilators be placed in intensive care?

Because this ventilation is invasive, patients are asleep 24 hours a day. They therefore need anesthetists and resuscitators alongside them. In addition, patients on a ventilator are regularly placed on their stomach to relieve the lower lungs, compressed while lying on their back. These ventral “cures” last 6 to 12 hours. “It takes a lot of people to turn them, turn them over, and we also need to position them correctly to prevent bedsores from occurring in the support areas. If a patient remains pressed on his cheekbone for twelve hours, the skin will become necrotic, ”further explains the practitioner. This risk is all the greater as many patients are “curarized”. The word is not chosen at random, it evokes curare, this paralyzing poison which coats the arrows of certain Indians of Amazonia. Doctors “curarize” patients to prevent muscle reflexes, which could cause a cough, bothersome to the device, or droplets of saliva, which are quick to disperse the virus.

How do we eat?

Patients on a ventilator are fed with a nasogastric tube, which has the advantage of keeping the digestive system in operation. The urine is evacuated by a urinary bag, regularly renewed.

Coronavirus: artificial respirators, the keystone of the medical response

Why does it take so much?

Since the multiplication of respiratory distress due to Covid-19, doctors note that artificial ventilation is twice as long, of the order of fifteen to twenty days, than for a serious flu. While waiting for the epidemic peak, which will necessarily be accompanied by an increase in hospitalizations, it will therefore require a lot of machines. How? That’s the whole question. The German Ministry of Health has ordered 10,000 from Drager. In France, Air Liquide has already accelerated its production. “Our engineers assembled 500 in March, we committed to release 1,100 in April. For devices manufactured in Pau, from 200 in March we will go to 600 in April, ”says one within the company. To make a fan, it takes a hundred parts, including electronic components, three to four hours of assembly, followed by a test phase then another aging.

How many respirators are there in France?

The census is in progress. In 2009, a survey by the sub-directorate for the organization of the health care system at the Ministry of Health estimated 7,007 the number of respirators in intensive care (compared to 9,236 three years earlier). A week ago, Jerôme Salomon, Director General of Health, said that France had “several tens of thousands of resuscitators”. “We have all kinds of other activities, transportation by Samu, operating theaters, recovery rooms, where you also have respirators,” he explained, to reassure. In the Great East, however, where serious cases explode, caregivers, for lack of equipment, had to sort through the sick.

Are there any consequences?

Yes. The longer a patient stays on an artificial respirator, the more serious the consequences of immobility will be, especially for the muscles that melt when they are no longer used. There will have to be a period of rehabilitation. To breathe naturally, swallow, but also to walk.

How much does a respirator cost?

Difficult to know, companies are not talkative on the subject. Drager refuses to communicate any information, believing “with humility and professionalism” to be only “support” for healthcare establishments. “For emergency respirators, it costs from 10 to 12,000 euros,” says the emergency room doctor, “those of the patient are around 40,000 €”. An industrialist in the sector recognizes that the most elaborate models can indeed reach this price.

Is there an alternative?

No, but there is a more invasive technique than the artificial respirator: ECMO, an acronym for “extracorporeal membrane oxygenation technique”. The ECMO completely bypasses the lung, the blood is directly oxygenated by a machine. “It’s a heavy treatment, you have to be able to hold the load. This is why it is reserved for young patients and in good general condition ”. This technique is only applied in major intensive care units, most of the time in CHUs, where patients must be transferred.

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